cosmopolitan/libc/tinymath/trunc.S

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/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
This program is free software; you can redistribute it and/or modify │
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License. │
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of │
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software │
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#include "libc/macros.h"
.source __FILE__
/ Rounds to integer, toward zero.
/
/ @param 𝑥 is double scalar in low half of %xmm0
/ @return double scalar in low half of %xmm0
/ @define trunc(𝑥+copysign(.5,𝑥))
/ @see round(),rint(),nearbyint()
/ @see roundsd $_MM_FROUND_TO_ZERO|_MM_FROUND_NO_EXC,%xmm0,%xmm0
tinymath_trunc:
.leafprologue
.profilable
movsd 3f(%rip),%xmm1
movsd 2f(%rip),%xmm2
andpd %xmm0,%xmm1
comisd %xmm1,%xmm2
jbe 1f
cvttsd2siq %xmm0,%rax
pxor %xmm0,%xmm0
cvtsi2sdq %rax,%xmm0
1: .leafepilogue
.endfn tinymath_trunc,globl
.alias tinymath_trunc,trunc
.rodata.cst8
2: .double 0x0010000000000000
3: .double nan